The next lower level of dealing with the OS command line are the
following words:

argu – addr count gforth “arg”

Return the string for the uth command-line argument; returns
0 0 if the access is beyond the last argument. 0 arg
is the program name with which you started Gforth. The next
unprocessed argument is always 1 arg, the one after that is
2 arg etc. All arguments already processed by the system
are deleted. After you have processed an argument, you can delete
it with shift-args.

shift-args– gforth “shift-args”

1 arg is deleted, shifting all following OS command line
parameters to the left by 1, and reducing argc @. This word
can change argv @.

Finally, at the lowest level Gforth provides the following words:

argc– addr gforth “argc”

Variable – the number of command-line arguments (including
the command name). Changed by next-arg and shift-args.

argv– addr gforth “argv”

Variable – a pointer to a vector of pointers to the
command-line arguments (including the command-name). Each argument
is represented as a C-style zero-terminated string. Changed by
next-arg and shift-args.